This invention relates to a method of and to apparatus for monitoring the concentration of a gas in a liquid.
The invention has particular application in the measuring and control of the content of carbon dioxide gas in beer and lager. The CO.sub.2 content in beer or lager is important in that the quality of the beer or lager is determined to some extent by the gas content which varies according to the eventual packaging of the beer. For example, canned and bottled beer require a higher gas content than kegged beer destined for draught.
Systems are known for measuring the CO.sub.2 content in beer but involve the use of a gas analyser which evaluates the CO.sub.2 volume concentration of a sample of the beer.
Such systems are to some extent impractical in so far as a delay neccessarily exists from the time the sample is taken to the time the results of the analysis are known and suitable adjustment of the quantity of CO.sub.2 injected is effected. Additionally, gas analysers are expensive pieces of equipment and it is not feasible to provide each production line in a large bottling plant with its own analyser, thus resulting in further delay before control can be carried out.